1. Field of the Invention
The present invention relates generally to supports for signs and similar structures, and more particularly to improvements in breakaway bases and connections for highway signs and the like. The present sign support utilizes set screws to lock the sign support pipe within the breakaway base or connector component, thereby precluding twisting or turning of the pipe within the base and corresponding misalignment of the sign.
2. Description of the Related Art
It has been recognized for some time that it is not desirable to construct highway sign supports and similar structures, of extremely durable and damage resistant materials. Generally, the impact forces from a motor vehicle hitting such a sign, result in severe damage to the vehicle and possible injury to the occupant(s) as well as destruction of the sign support structure. Moreover, the additional cost of the sign structure for such relatively strong and massive sign supports, results in considerably greater costs in labor and materials to replace such a sign when it is damaged.
As a result, a number of different assemblies have been developed to provide an intentionally weak highway sign structure which will flex, break, and/or disassemble upon impact by a vehicle. It is of course desirable to provide a structure which will disassemble upon impact without damage to components, in order to allow the previously used components to be reassembled without requiring replacement of any significant or costly components (other than perhaps small fasteners, etc.).
One such sign support system which has been developed, is the Texas Universal Triangular Slipbase System (TUTSS). This system utilizes mating triangular plates having notched apices, with bolts installed at each apex to clamp the apices of the plates together. Shear forces caused by an impact, result in the two plates moving apart from one another in shear and dislodging the bolts from their apex notches in the triangular plates. Most, if not all, of the structure is reusable and may be reassembled after an impact, with the impact possibly resulting in the need to replace the readily available and inexpensive post or pipe, bolts, nuts, etc.
The TUTSS assembly utilizes a specially configured slipbase component, having a relatively large diameter relief area formed within the base of the pipe attachment collar at its juncture with the triangular plate. This relief area is provided for clearance for a split ring collar, which is tightened around the base of the pipe after passing the slipbase component over the end of the pipe. The split ring collar is captured by the slipbase component and prevents the pipe from being pulled from the slipbase.
The problem with the split ring collar support pipe retention structure, is that the cylindrical pipe can turn within the collar unless an excessive amount of force is used to tighten the pinch bolt of the collar in place on the pipe. While this may not be so critical for signs utilizing multiple support columns, a sign having a single support pipe or column, may turn or rotate within the slipbase collar. This is particularly a problem in areas of high winds, where aerodynamic forces can cause the relatively large plate area of the sign to flutter or work back and forth in the wind. This produces a torsion on the pipe or post holding the sign, which torsional force is transmitted down the pipe to the slipbase and collar contained therein. The collar may turn on the pipe, and/or the collar may turn relative to the slipbase, unless the various bolts holding the assembly together are extremely tight.
Standards call for the pinch bolt on the collar to be tightened to a torque of sixty foot-pounds, with the three apex bolts securing the slipbase components together being tightened to forty foot-pounds of torque. Even these high torque values still fail to prevent a sign on a single support pipe, from gradually rotating or twisting the pipe relative to the slipbase assembly. It has been found that in areas of high wind, that maintenance crews sometimes have to realign signs using this system, as often as once a week. The costs of this frequent maintenance can result in the cost of the sign being many times the initial purchase and installation cost, over the life of the sign.
It will be appreciated that the realignment of signs using the TUTSS assembly is not a trivial task, as it requires the mechanic to loosen the three apex bolts securing the slip base components together, slide the upper slipbase up the pipe to access the split collar and its pinch bolt, retorque the pinch bolt as required, realign the sign, and tighten the three slipbase apex bolts to the proper torque. This procedure requires at least a few minutes, in addition to the travel time and costs of operating a vehicle to travel to the site where the sign is located.
The present invention responds to this problem by locking the base of the post or pipe into the slipbase by means of a series of set screws, which penetrate the side walls of the slipbase collar and engage the walls of the pipe. The point compression of the setscrews into the side wall of the pipe, prevents rotation of the pipe within the slipbase collar. Thus, once the sign post assembly of the present invention has been assembled, no further periodic maintenance is required in order to maintain the alignment of the sign and post relative to the mounting base. The present system thus provides significant cost savings in terms of maintenance, over the life of the sign.
A discussion of the related art of which the present inventors are aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 1,575,040 issued on Mar. 2, 1926 to Rufus M. Crum, titled “Flagpole,” describes a hinged pole assembly in which the upper portion of the pole is pivotally secured to the upper end of the stationary lower portion. The bottom end of the pivoting upper portion extends downwardly past the pivot hinge to seat within the stationary lower portion of the pole, where it is pinned in an upright position by a removable bolt. This arrangement allows the upper portion of the pole to be lowered for installation or removal of a flag to or from its upper end. Crum does not provide any form of shear plates which are secured together by bolts to allow the upper and lower portions to separate from one another, as is the case with the present sign support invention.
U.S. Pat. No. 3,451,319 issued on Jun. 24, 1969 to Hans E. Gubela, titled “Road Guidepost,” describes a sign post comprising a wood core with a plastic shell or cover. A tapered attachment flange is provided at the top of the base which is installed in the ground, with a tapered shoe being secured to the bottom end of the post and engaging the flange of the base. Impact with the post dislodges the shoe from the flange, allowing the post to be reinstalled to the base. However, the Gubela assembly is unidirectional, due to the taper of the components, and can only be assembled in one orientation. Moreover, the manufacture of the wood core with its plastic cover is relatively labor intensive, thus resulting in considerably higher manufacturing costs than the present sign post formed of a length of stock pipe material.
U.S. Pat. No. 3,521,917 issued on Jul. 28, 1970 to Charles E. King, titled “Positive Action Clamp,” describes a sign having a permanently installed base with a breakaway upper column or post. Two opposed cheek plates are attached to the bottom end of the upper portion by spring compression bolts and nuts which pass through the post and cheek plates. Lateral force on the upper portion of the sign causes the cheek plates to spread against the compression of the springs, thereby allowing the upper portion of the sign to break loose from its attachment to the lower portion. Longitudinal force causes the upper portion of the sign to pivot about its lower end which rests upon the fixed bottom column, again allowing the upper portion to break loose from the lower portion. However, the King sign assembly with its opposed cheek plates is only adaptable to square or rectangular section posts, and no mating, horizontally shearing plates are provided by King for connecting cylindrical sign column components.
U.S. Pat. No. 3,792,680 issued on Feb. 19, 1974 to Francis R. Allen, titled “Flag Pole,” describes a hinged pole assembly with an upper portion which is hingedly attached to a fixed lower portion. The lower end of the upper portion is counter weighted and nests within the hollow upper portion of the fixed lower end of the assembly when the upper portion of the pole is erected. The upper portion of the Allen pole cannot break away from the lower portion without damage. The Allen assembly thus more closely resembles the flagpole of the '040 U.S. Patent to Crum, discussed further above, than it does the present assembly.
U.S. Pat. No. 3,820,906 issued on Jun. 28, 1974 to Herbert L. Katt, titled “Highway Sign Post,” describes a specially configured, frangible assembly for use in assembling lengths of channel end to end in a highway sign post. One component comprises a casting or the like having a generally U-shaped cross section, with a groove formed medially thereabout to provide a line of weakening. A second component bolts to the opposite side of the channel, to sandwich the two ends of the channel therebetween. Impact on the upper channel causes the U-shaped casting to break along its line of weakening and also breaking the second component. The lower bolt holding the assembly to the lower portion of the channel, bends as the upper portion of the sign is pushed over but continues to hold all of the components together. Katt thus teaches away from the present invention, which provides for separation of the sign post components without damage to any significant or costly components thereof.
U.S. Pat. No. 4,032,248 issued on Jun. 28, 1977 to Alfred P. Parduhn et al., titled “Articulated Highway Delineator Post,” describes a two piece post formed of channel sections, with a sleeve having one open side connecting the two sections together end to end. When the upper portion of the post is struck, the lower end pivots about its attachment in the sleeve to extend out of the open side of the sleeve. The Parduhn et al. assembly thus remains completely assembled and does not separate, as does the present sign post assembly.
U.S. Pat. No. 4,052,826 issued on Oct. 11, 1977 to Douglas B. Chisholm, titled “Breakaway Coupling Assembly With Fracture-Initiating Washer,” describes various embodiments of a cylindrical sleeve having a partially threaded core and a series of weakening grooves in the outer surface thereof. The sleeves are used to support a base plate, with bolts passing through the base plate and engaging the threaded cores of the sleeves. A washer having a toothed surface is installed between each sleeve and the plate. Bending force upon a pole or the like supported by the base plate, results in excessive compressive force being applied to the sleeves to the side away from the compressive force. This drives the toothed washers downwardly against the sleeves, fracturing the sleeves along their weakening lines and allowing the assembly to collapse. The Chisholm sleeves are specialized components which must be replaced after the sign is displaced, whereas all specialized components of the present system are reusable.
U.S. Pat. No. 4,926,592 issued on May 22, 1990 to Charles O. Nehls, titled “Breakaway Sign Post Coupling,” describes several different embodiments of an assembly essentially comprising a pair of opposed, triangular plates with notched apices. Bolts are installed in the notches to secure the plates together. Each plate has an additional component extending therefrom, which accepts a post therein. An impact upon the upper post causes the two plates to separate in horizontal shear, with the bolts dislodging from their positions in the notches of the triangular plates. In one embodiment (FIG. 8), a cylindrical pipe is installed in the upper connector component. This assembly is the earliest example of which the present inventors are aware, of pairs of opposed triangular slip bases being used to secure a separable upper post to a fixed lower post. The Nehls assembly is also similar to the structure of the Texas Universal Triangular Slipbase System (TUTSS), noted further above. However, Nehls does not provide a collar integrally formed with the triangular plates, which collar completely surrounds the associated end of the cylindrical pipe component, as provided by the present invention. Moreover, Nehls bolts the ends of the pipes (or other elongate posts) completely through the posts and upright post mounting components extending from the triangular plates. Separation of the posts from their respective fittings, would require removal or destruction of the bolts. In contrast, the set screws of the present arrangement hold the post securely in place, but still allow withdrawal of the post from the corresponding fitting without damage to the fasteners or requiring removal thereof, when excessive force is applied.
U.S. Pat. No. 5,749,189 issued on May 12, 1998 to Dan Oberg, titled “Post Device,” describes a socket for installing a pipe or the like therein. The socket includes a series of radially disposed lugs, through which corresponding bolts or studs are installed to secure the socket to an underlying concrete pad or the like. The lugs have open sides, which allow the bolts to pull free in the event the socket is dislodged from its base due to impact with the pole extending therefrom. Oberg does not disclose any means for securing the pole within the socket, however.
U.S. Pat. No. 5,855,443 issued on Jan. 5, 1999 to Ronald K. Faller et al., titled “Breakaway Connection System For Roadside Use,” describes an assembly comprising a pair of parallel plates welded to the adjacent ends of a base and an extension pole. A series of bolts are installed through holes in the plates, with one or more collars or shearing plates installed on each bolt between each of the parallel plates. When the upper pole is struck, the relatively larger diameters of the collars impart shearing forces upon the relatively smaller diameters of the connecting bolts, thereby breaking the bolts and allowing the upper portion of the sign to break away from the fixed base. As the bolts pass through holes in the plates, they cannot escape from the plates and must break in order to allow the upper portion of the structure to break away. Also, it is noted that the posts are welded to the plates, and cannot be replaced after impact damage. In contrast, the bolts securing the two subassemblies of the present sign structure together and the pipe(s) or post(s) of the structure, may be reused or replaced as separate components, as required.
U.S. Pat. No. 6,254,063 issued on Jul. 3, 2001 to John R. Rohde et al., titled “Energy Absorbing Breakaway Steel Guardrail Post,” describes a series of embodiments for guard rail posts, each including some means of predictable failure in a given direction. Each of the embodiments includes some component(s) (cables, shear plates, and/or bolts) which are damaged as a result of impact force on the guard rail supported by the post, with such damaged components requiring replacement, unlike the present invention.
U.S. Pat. No. 6,264,162 issued on Jul. 24, 2001 to Theodore D. Barnes et al., titled “Breakaway Sign Post,” describes an assembly having a frangible collar joining the base and upper sections of the post. The collar includes vertically disposed slots therein, which allow the portion of the collar wall defined by the slots to fold when the upper portion of the post assembly is struck. The components of the Barnes et al. post assembly do not separate from one another, and the Barnes et al. collar must be replaced after the upper post is bent over. The Barnes et al. post assembly thus more closely resembles the post assembly of the Katt '906 U.S. patent, discussed further above, than it does the present invention.
Canadian Patent Publication No. 973,677 issued on Sep. 2, 1975 to John Shewchuck, titled “Coupling For Break Away Pole Bases,” describes a system wherein a pole is supported above a base by a series of frangible spacers. An impact force on the pole causes the spacers to break, thereby allowing the pole to separate from the base and fall rather than resisting the impact. The same problem occurs here as has been noted further above in the discussion of other assemblies having frangible components, i.e., the specially formed frangible components must be replaced before the pole or post assembly can be reassembled. These frangible components are generally specially made and are therefore relatively costly, in comparison to “off the shelf” stock items such as conventional bolts, etc. The present invention enables most, if not all, components to be reused after an impact.
German Patent Publication No. 1,255,128 published on Nov. 30, 1967 illustrates a post having a base bracket with a pair of laterally spaced bolts passing therethrough and through the bottom of the post seated in the bracket. The bracket also includes opposed, inwardly turned flanges which penetrate the wood post along opposite sides thereof. If a post having this construction were to be impacted, either the bottom of the post, the bracket, or the bolts, or some combination of these components, would be damaged and would require replacement, unlike the present post or pole assembly.
Finally, the inventors are aware of an assembly manufactured by the P. & H. Tube Corporation of Houston, Tex., titled the “Poz-Loc Slip-Base System.” The Poz-Loc System comprises a series of embodiments, each having a pair of triangular slip base plates which are secured to the adjacent ends of an anchor post and a second post extending upwardly therefrom. Each of the triangular plates includes a notch at each apex, with a bolt being installed through each notch to hold the plates together. This system is similar to that described in the Nehls '592 U.S. patent, with the present invention also utilizing paired triangular slip base plates having notched apices for the connecting bolts. The triangular slip base plate of the Poz-Loc base post is permanently attached thereto (welded, etc.), while the slip base plate of the upper post section includes a cylindrical sleeve, into which the lower end of the upper post is installed. The sleeve of the upper slip base plate is installed over the lower end of the upper post, and a split ring collar is installed between the slip base plate and the lower end of the post to retain the upper slip base plate on the upper post. The collar is secured by means of a pinch bolt. The Poz-Loc System meets the standards of the Texas Universal Triangular Slipbase System (TUTSS), but a problem arises when posts having a cylindrical shape (i.e., pipe, round tubing, etc.) is used in an assembly comprising a single post, as in the case of a relatively small sign (stop sign, etc.). In conditions of high wind, and/or gusts created by passing vehicles (particularly large trucks), the wind may impart sufficient force on the flat plate of the sign to produce significant torsional loads on the post to which the sign is attached. The sign generally cannot turn on the post, as such signs are generally attached by means of through bolts or other fastening means which preclude rotation of the sign relative to the post. However, the torsional force produced by the sign is transferred to the post, where it attempts to turn the base of the post in the slip base. The upper slip base cannot turn, as it is bolted to the fixed lower slip base by means of the three apex bolts. However, the upper pipe can turn or rotate within the sleeve of the upper triangular slip base plate, even though it is held in place by the split ring collar. It is extremely difficult to torque the pinch bolt of the collar sufficiently to completely immobilize the base of the upper post within the collar, and/or to clamp the two slip bases sufficiently to immobilize the collar therebetween. In high wind conditions, a sign supported by the Poz-Loc system can rotate out of its desired alignment where it is visible to drivers, within a week or so of adjustment. The Poz-Loc system requires regular and frequent maintenance in order to maintain the alignment of signs supported thereby, with the maintenance requiring the entire slip base assembly to be disassembled in order to access the pinch bolt of the split collar for retorquing of that bolt. In contrast, the present system utilizes a series of set screws which pass through the walls of the cylindrical sleeve of the slip base, and engage the pipe installed therein. No separate collar is used with the present sign support system. It is impossible for the sign support pipe to rotate within the slip base plate using the set screws of the present invention which penetrate the walls of the slip base sleeve and engage the pipe therein, to immovably affix it in place.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus a breakaway post base solving the aforementioned problems is desired.